At the risk of stating the blatantly obvious...
Centralized architecture allows centralized control, notably over promotion and moderation. Facebook, Twitter/X, and other centralized platforms are absolutely responsible for what they promote and what they moderate. That someone could state otherwise staggers belief.
Decentralized architectures allow for more freedom of providers, content promotion and moderation policies, and apps.
To sum, the protocol and architecture changes everything.
Also, plenty of software freedom activists choose platforms based on protocol and architecture. Myself included, so you've now met at least one. :)
